void main() {
  Map category = {'name': '苗子怡', 'age': 22};
  print(category);
  print(category['name']);

  category['name'] = '范怡博';
  print(category);

  category['sex'] = '男';
  print(category);

  category.remove('age');
  print(category);

  category.forEach((key, value) {
    print('key = $key, value = $value');
  });
}
